If you're talking about checking out Rhapsody, or as they're now known, Rhapsody of Fire, you need to be aware of a few things:
They're incredible musicians. Luca Turulli may be the best guitarist in metal, and that's saying a lot.
You will crack up over their lyrics. A lot. Especially on their earlier stuff. They're Italian, but they perform in English, and some of their pronunciation is...interesting. F'rinstance, they pronounce "Emerald Sword" "Eem-er-ahld sWARd." And their early narrative bits were laughable. But they've gotten Christopher Lee to do stuff on their last few albums, which lends a certain gravitas to the proceedings. Nonetheless, they are kind of dorky. No, make that a LOT dorky. They've done over a half-dozen albums telling the epic tale of one fantasy world and even have a map of it up on their website.
For a quick introduction, I recommend the following sites:
Rhapsody of Fire's Myspace Page
Their official website
Full-length video for "Unholy Warcry" (With lots of Christopher Lee. Also, keyboards in the woods!)
"Unholier Warcry", a parody of the above, because if you can't laugh at metal once in a while, you're taking life way too serious.